Terminal clustering

ABSTRACT

A method includes checking for a first cluster beacon associated with a first cluster. The first cluster is an open cluster. The method further includes transmitting a second cluster beacon associated with a second cluster. Transmitting the second cluster beacon is done in response to failing to receive the first cluster beacon. The method further includes receiving a first request in response to transmitting the second cluster beacon. The first request includes a request by a first terminal to join the second cluster. The method further includes receiving a second request in response to transmitting the second cluster beacon. The second request includes a request by a second terminal to join the second cluster.

FIELD

The embodiments discussed herein are related to terminal clustering.

BACKGROUND

Terminal-to-terminal communication may allow data transmissions to bemade directly between two or more terminals of a telecommunicationsystem. The terminal-to-terminal communication may overlay regularcellular communications, and may be performed with or without cellularnetwork coverage.

In some instances, using terminal-to-terminal communication may increasenetwork capacity. For example, terminal-to-terminal communication maypermit spatial multiplexing, which may allow for higher relativespectrum usage. Employing terminal-to-terminal communication may alsopermit throughput between terminals to be increased if aterminal-to-terminal link experiences better channel quality than acellular link. Using terminal-to-terminal communication may reduceresource usage when data is transmitted once between two terminalsduring a terminal-to-terminal transmission, as compared to transmittingthe same data twice between the two terminals over a cellular link,i.e., once through an uplink (UL) transmission from a transmittingterminal to a base station and once through a downlink (DL) transmissionto a receiving terminal from the base station.

Terminal-to-terminal communication may reduce communication latency of atelecommunication network. For example, terminal-to-terminalcommunication may not relay data through a base station and/or a corenetwork, thus potentially reducing the transit time of the data and/orthe load on the base station and/or the core network.

The subject matter claimed herein is not limited to embodiments thatsolve any disadvantages or that operate only in environments such asthose described above. Rather, this background is only provided toillustrate one example technology area where some embodiments describedherein may be practiced.

SUMMARY

According to an aspect of an embodiment, a method includes checking fora first cluster beacon associated with a first cluster. The firstcluster is an open cluster. The method further includes transmitting asecond cluster beacon associated with a second cluster. Transmitting thesecond cluster beacon is done in response to failing to receive thefirst cluster beacon. The method further includes receiving a firstrequest in response to transmitting the second cluster beacon. The firstrequest includes a request by a first terminal to join the secondcluster. The method further includes receiving a second request inresponse to transmitting the second cluster beacon. The second requestincludes a request by a second terminal to join the second cluster.

The object and advantages of the embodiments will be realized andachieved at least by the elements, features, and combinationsparticularly pointed out in the claims.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and arenot restrictive of the invention, as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

Example embodiments will be described and explained with additionalspecificity and detail through the use of the accompanying drawings inwhich:

FIG. 1 is a diagrammatic view of an example telecommunication system;

FIG. 2 is a diagrammatic view of an example cluster that may beimplemented in the telecommunication system of FIG. 1;

FIG. 3 is a diagrammatic view of example clusters having a terminallocated within an overlap of the example clusters;

FIG. 4 is a diagrammatic view of example clusters having a clustermember located within an overlap of the example clusters;

FIG. 5 is a diagrammatic view of an example communication process ofassociating a terminal with a cluster having a cluster head; and

FIG. 6 is a flowchart of an example method of forming a cluster.

DESCRIPTION OF EMBODIMENTS

Some embodiments described herein may relate to a telecommunicationsystem based on the 3rd Generation Partnership Project's (3GPP) LongTerm Evolution (LTE) radio access network. Descriptions involving LTEmay also apply to 3GPP's Long Term Evolution Advanced (LTE-A) radioaccess network. However, the embodiments described herein are notlimited to the example telecommunication systems described. Rather, theembodiments described herein may also be applicable to othertelecommunication systems.

Embodiments of the present invention will be explained with reference tothe accompanying drawings.

FIG. 1 is a diagrammatic view of an example telecommunication system100, arranged in accordance with at least one embodiment describedherein. In some embodiments, a network architecture of thetelecommunication system 100 may include the network architecture of anEvolved Universal Mobile Telecommunications System (E-UMTS). The E-UMTSmay include an LTE radio access network, for instance. The radio accessnetwork may include an E-UMTS Terrestrial Radio Access Network(E-UTRAN). However, other types of network architecture may alternatelyor additionally be used.

The telecommunication system 100 may include a base station 102. Thebase station 102 may include base station equipment, including hardwareand/or software for radio communication withradio-communication-equipped nodes (“wireless nodes”) which may bedescribed herein as devices. For example, the base station 102 may beequipped for radio communication 110 with devices such as terminal 104a, terminal 104 b, and terminal 104 c (collectively “terminals 104”).The base station 102 may generally allow the wireless nodes, includingthe terminals 104, to wirelessly communicate with each other and/or towirelessly access a network (not shown) via radio communication 110 withthe base station 102.

The base station 102 may include hardware and software for radiocommunication over a licensed spectrum. The licensed spectrum maygenerally include portions of a radio spectrum licensed for transmissionof wireless data, such as cellular data. For example, the base station102 may be configured to transmit cellular data that complies with anLTE radio access network, such as an LTE radio access network accordingto 3GPP LTE specification releases 8-12. The base station 102 mayinclude an E-UTRAN NodeB (eNB) associated with LTE radio accessnetworks.

The terminals 104 may include equipment configured to allow theterminals 104 to transmit and receive data via wireless communicationsvia the licensed spectrum. For example, the terminals 104 may includehardware, such as one or more antennas for transmitting and receivingradio transmissions, and codecs. The terminals 104 may include mobilephones, tablet computers, laptop computers, and/or other electronicdevices that may use radio communication. Alternately or additionally,the terminals 104 may include devices that employ machine-typecommunication (MTC). The terminals 104 may include user equipment (UE)associated with LTE radio access networks.

Each of the terminals 104 may include memory 106 and a processor 108.The memory 106 may include a non-transitory computer-readable medium.Instructions such as programming code executable by the processor 108may be encoded in the memory 106. When the instructions are executed bythe processor 108, the associated terminals 104 a, 104 b, and 104 c mayperform operations related to and/or including the processes describedherein.

The terminals 104 may be equipped for terminal-to-terminal communication112, which may include device-to-device (D2D) communication associatedwith LTE radio access networks. The terminal-to-terminal communication112 may allow the terminals 104 to transmit and/or receive data amongthe terminals 104 without routing the data through the base station 102.

FIG. 2 is a diagrammatic view of an example cluster 200. In someembodiments, the cluster 200 may be implemented in the exampletelecommunication system 100 of FIG. 1. The cluster 200 may include acluster head 202. The cluster 200 may also include a cluster member 206a, a cluster member 206 b, a cluster member 206 c, and a cluster member206 d (collectively “cluster members 206”). The cluster members 206 maybe terminals generally corresponding to the terminals 104 of FIG. 1. Thecluster members 206 may be within a transmission range 204 of thecluster head 202. The cluster members 206 may or may not be within atransmission range (not shown) of each of the other cluster members 206.The cluster 200 may enable cluster-member-to-cluster-membercommunication 210. The cluster-member-to-cluster-member communication210 may generally correspond to the terminal-to-terminal communication112 of FIG. 1.

In some embodiments, the cluster head 202 may be a base stationgenerally corresponding to the base station 102 of FIG. 1. For example,a base station may be the cluster head 202 for cluster members 206located within a cell generally corresponding to the transmission range204 of the base station. In embodiments including a base station as thecluster head 202, a cluster-member-to-cluster-head communication 208 maygenerally correspond to the radio communication 110 of FIG. 1. In someembodiments, when the cluster head 202 is a base station, one or moreterminals generally corresponding to the terminals 104 of FIG. 1associated with the base station for cellular communication may becluster members 206.

Alternately, the cluster head 202 may be a terminal generallycorresponding to the terminals 104 of FIG. 1. For example, a terminalmay be the cluster head 202 for cluster members 206 located within atransmission range 204 of the terminal acting as the cluster head 202.The terminal acting as the cluster head 202 and/or one or more of thecluster members 206 may be outside of cellular network coverage, e.g.,the cluster head 202 and/or one or more of the cluster members 206 maybe outside of a transmission range of a base station. In embodimentsincluding a terminal as the cluster head 202, thecluster-member-to-cluster-head communication 208 may generallycorrespond to the terminal-to-terminal communication 112 of FIG. 1.

In some embodiments, when the cluster head 202 is a terminal, otherterminals may perform a communication process with the cluster head 202to become cluster members 206. The cluster head 202 may transmit acluster beacon. In some embodiments, resources for the cluster beaconmay be configured through a radio resource control (RRC). The clusterbeacon may advertise the existence of the cluster 200 and/or may provideinformation to be used by terminals to join the cluster 200 as one ofthe cluster members 206.

In some embodiments, the cluster beacon may identify resources allocatedfor a cluster random access channel (C-RACH) procedure. Alternately oradditionally, the cluster head 202 may identify resources allocated forthe C-RACH procedure in a cluster physical broadcast channel (C-PBCH).

The cluster beacon may be transmitted by the cluster head 202periodically. Alternately, the cluster beacon may be transmitted by thecluster head 202 pseudo-periodically or randomly. For example, thecluster head 202 may transmit the cluster beacon at random time offsetsapplied to regular periods.

The cluster beacon may include cluster control information. In someembodiments, the cluster control information may include a clusteridentifier associated with the cluster 200. The cluster identifier mayinclude a cluster number. As set forth below, in some embodiments, arelative value of the cluster number may affect the likelihood that aterminal attempts to join the cluster 200. The cluster head 202 maychoose a cluster number from a range of cluster numbers based on anumber of factors such as battery status, functionality of the clusterhead 202, and/or the like.

The cluster control information may further include a timesynchronization indicator. The time synchronization indicator mayindicate whether the cluster head 202 is time-synchronized with areliable external timing source. A reliable external timing source mayinclude, for example, a global positioning service (GPS) timing source,a broadcast network, a cellular network, or the like or any combinationthereof. In some embodiments, the time synchronization indicator mayinclude a cluster synchronization (C-SYNC) bit.

In some embodiments, the cluster control information may further includea cluster status indicator. The cluster status indicator may beconfigured to indicate a relative available capacity of the cluster 200.For example, the cluster status indicator may include a two-bit clusterstatus (CS) representing the relative available capacity of the cluster200 as set forth in the following table. Other relative availablecapacities may alternately or additionally be represented in the clusterstatus.

CS Relative Available Capacity 00 No cluster members 206 in cluster 200;cluster members 206 welcome to join the cluster 200. 01 One or morecluster members 206 in cluster 200; additional cluster members 206 arewelcome to join the cluster 200. 10 Number of cluster members 206 in thecluster 200 is near a capacity of the cluster 200; additional clustermembers 206 may still join the cluster 200. 11 Number of cluster members206 in cluster 200 is at capacity of the cluster 200; additional clustermembers 206 may not join the cluster 200.

Alternately, the cluster status indicator may include a one-bit clusterstatus representing whether the cluster 200 is at capacity or not atcapacity, i.e., the cluster status may represent whether the cluster 200is an open cluster or a closed cluster. Other cluster status indicatorsmay alternately or additionally be included in the cluster controlinformation.

FIG. 3 is a diagrammatic view of two example clusters 300 a and 300 bhaving a terminal 308 located within an overlap of the clusters 300 aand 300 b. The cluster 300 a may include a cluster head 302 a and thecluster 300 b may include a cluster head 302 b. The cluster head 302 aand the cluster head 302 b may each generally correspond to the clusterhead 202 of FIG. 2. In some embodiments, the cluster head 302 a and thecluster head 302 b may both be terminals. Alternately, the cluster head302 a may be a base station and the cluster head 302 b may be aterminal, or vice versa. Although two clusters 300 a and 300 b areshown, these and other embodiments may alternately or additionally applyto three or more overlapping clusters.

The cluster head 302 a may have a transmission range 304 a generallycorresponding to the transmission range 204 of FIG. 2. The cluster head302 b may have a transmission range 304 b generally corresponding to thetransmission range 204 of FIG. 2.

The cluster 300 a may further include a cluster member 306 a, a clustermember 306 b, and a cluster member 306 c generally corresponding to thecluster member 206 a, the cluster member 206 b, and the cluster member206 c of FIG. 2. The cluster 300 b may also further include a clustermember 306 d, a cluster member 306 e, and a cluster member 306 fgenerally corresponding to the cluster member 206 a, the cluster member206 b, and the cluster member 206 c of FIG. 2.

The cluster 300 a and the cluster 300 b may include some elements thatare similar or identical to elements of the cluster 200 of FIG. 2, suchas the cluster-member-to-cluster-head communication 208 and thecluster-member-to-cluster-member communication 210, for which a moredetailed description is already provided above.

The terminal 308 may desire to join a cluster and may check for clusterbeacons 310 a and 310 b. In response to receiving only one clusterbeacon, e.g., if the cluster beacon 310 a is received and the clusterbeacon 310 b is not received, or in response to receiving only onecluster beacon associated with an open cluster, e.g., if the cluster 300a has available capacity and the cluster 300 b is at maximum capacity,the terminal 308 may respond to the cluster beacon 310 a by transmittinga request to join the cluster 300 a associated with the cluster beacon310 a. If one or both of the cluster beacons 310 a and 310 b includes acluster status indicator that indicates that the cluster 300 a and/orthe cluster 300 b are at capacity, the terminal 308 may consider thecluster 300 a and/or the cluster 300 b closed and may not choose to jointhe cluster 300 a and/or the cluster 300 b.

In response to receiving multiple cluster beacons 310 a and 310 b, theterminal 308 may choose to join one of the clusters 300 a and 300 bbased on a prioritization of the cluster 300 a relative to the cluster300 b. Determining the priorities of each of the clusters 300 a and 300b may be based on the cluster control information included in thecluster beacons 310 a and 310 b.

In some embodiments, the terminal 308 may assign a higher priority to atime-synchronized cluster relative to a non-time-synchronized cluster.For example, the terminal 308 may choose to join the cluster 300 a overthe cluster 300 b in response to the cluster beacon 310 a indicatingthat the cluster head 302 a is time-synchronized with a reliableexternal timing source and the cluster beacon 310 b indicating that thecluster head 302 b is not time-synchronized with a reliable externaltiming source.

In some embodiments, the terminal 308 may assign a higher priority to acluster with a higher available capacity relative to a cluster with alower available capacity. For example, the terminal 308 may choose tojoin the cluster 300 a over the cluster 300 b in response to a clusterstatus indicator of the cluster beacon 310 a indicating that the cluster300 a has an available capacity that is higher than the availablecapacity of the cluster 300 b, as indicated by the cluster beacon 310 b.In some embodiments, the terminal 308 may consider the availablecapacity of the clusters 300 a and 300 b in response to the clusters 300a and 300 b both being time-synchronized or both not beingtime-synchronized.

In some embodiments, the terminal 308 may assign a higher priority to acluster having a cluster head with a lower mobility relative to acluster having a cluster head with a higher mobility. Mobility of thecluster head 302 a and the cluster head 302 b may be based onobservations of one or more qualities of the associated cluster beacons310 a and 310 b over time. By way of example, the terminal 308 maychoose to join the cluster 300 a over the cluster 300 b if the terminal308 determines that the cluster head 302 a is less mobile relative tothe cluster head 302 b. In some embodiments, the terminal 308 mayconsider the relative mobility of the cluster heads 302 a and 302 b inresponse to the cluster 300 a and the cluster 300 b both beingtime-synchronized or both not being time-synchronized, and/or thecluster 300 a and the cluster 300 b both having the same or similaravailable capacities.

In some embodiments, the terminal 308 may assign a relative priority toclusters based on the associated cluster identifiers. For example, theterminal 308 may choose to join the cluster 300 a over the cluster 300 bif the cluster beacon 310 a includes a cluster identifier having acluster number higher than a cluster number included in a clusteridentifier of the cluster beacon 310 b. In some embodiments, theterminal 308 may consider the relative value of the cluster numbers inresponse to the clusters 300 a and 300 b both being time-synchronized orboth not being time-synchronized, the cluster 300 a and the cluster 300b both having the same or similar available capacities, and/or themobility of the cluster head 302 a and the cluster head 302 b being thesame or similar.

In some embodiments, the terminal 308 may prioritize the clusters 300 aand 300 b according to a progression of considerations. For example, theterminal 308 may first prioritize the clusters 300 a and 300 b based onwhether the cluster 300 a and/or the cluster 300 b aretime-synchronized. If one of the clusters 300 a and 300 b has a higherpriority, the terminal 308 may join the higher-priority cluster. If theclusters 300 a and 300 b have the same priority, in some embodiments,the terminal 308 may prioritize the clusters 300 a and 300 b based onthe available capacity of the clusters 300 a and 300 b.

In response to the clusters 300 a and 300 b maintaining the samerelative priority, the progression of considerations may continue untilthe terminal 308 determines that one of the clusters 300 a and 300 b hasa higher priority. For example, the terminal 308 may prioritize theclusters 300 a and 300 b based on the mobility of the associated clusterheads 302 a and 302 b, and potentially may prioritize the clusters 300 aand 300 b based on the associated cluster identifier. Other factors mayalternately or additionally be considered in prioritizing the clusters300 a and 300 b.

In some embodiments, the terminal 308 may join both the cluster 300 aand the cluster 300 b. FIG. 4 is a diagrammatic view of a cluster 400 aand a cluster 400 b having a shared cluster member 406 d located withinan overlap. The cluster 400 a may include a cluster head 402 a, and thecluster 400 b may include a cluster head 402 b. The cluster heads 402 aand 402 b may generally correspond to the cluster head 202 of FIG. 2.The cluster 400 a may include a cluster member 406 a, a cluster member406 b, a cluster member 406 c, and the shared cluster member 406 d. Thecluster 400 b may include a cluster member 406 e, a cluster member 406f, a cluster member 406 g, and the shared cluster member 406 d. Theshared cluster member 406 d and the cluster members 406 a, 406 b, 406 c,406 e, 406 f, and 406 g may generally correspond to the cluster members206 of FIG. 2.

The cluster 400 a and the cluster 400 b may include some elements thatare similar or identical to elements of the cluster 200 of FIG. 2, suchas the cluster-member-to-cluster-head communication 208 and thecluster-member-to-cluster-member communication 210, for which a moredetailed description is already provided above.

The shared cluster member 406 d may switch operation between the cluster400 a and the cluster 400 b. For example, the shared cluster member 406d may use a discontinuous reception (DRX) mode to follow a time-divisionmultiple access (TDMA) schedule between the cluster 400 a and thecluster 400 b.

In some embodiments, the shared cluster member 406 d may relaycommunications between the cluster 400 a and the cluster 400 b. Forexample, the shared cluster member 406 d may receive a communicationfrom the cluster 400 a, e.g., the shared cluster member 406 d mayreceive a communication from the cluster head 402 a, the cluster member406 a, the cluster member 406 b, and/or the cluster member 406 c. Theshared cluster member 406 d may transmit the communication to thecluster 400 b, e.g., the shared cluster member 406 d may transmit thecommunication to the cluster head 402 b, the cluster member 406 e, thecluster member 406 f, and/or the cluster member 406 g.

FIG. 5 is a diagrammatic view of an example communication process 500 ofassociating a terminal 504 with a cluster having a cluster head 502. Insome embodiments, the communication process 500 may include a clusterrandom access channel (C-RACH) procedure.

The communication process 500 may begin with the cluster head 502transmitting a cluster beacon 506 that is received by the terminal 504.

The communication process 500 may continue with the terminal 504transmitting a request 508 to join the cluster that is received at thecluster head 502. The request 508 may include a cluster identifierincluded in the cluster beacon 506. In some embodiments, the request 508may include a C-RACH request (C-RACH-REQ).

In some embodiments, the communication process 500 may continue with thecluster head 502 transmitting a response 510 to the terminal 504. Theresponse 510 may identify resources allocated for a reply 512. Theresponse 510 may include a C-RACH response (C-RACH-RSP). In someembodiments, the communication process 500 may continue with theterminal 504 transmitting the reply 512 to the cluster head 502. Thereply 512 may include information about the terminal 504, informationabout the link between the cluster head 502 and the terminal 504, and/orthe like. The reply 512 may include a C-RACH reply (C-RACH-REPLY).

The communication process 500 may continue with the cluster head 502transmitting a confirmation 514. The confirmation 514 may include acluster-specific identifier for the terminal 504. For example, theconfirmation 514 may include a cluster radio-network temporaryidentifier (C-RNTI) as an identifier for the terminal 504 in thecluster.

Referring again to FIG. 2, connectivity between the cluster head 202 andthe cluster members 206, and/or connectivity among the cluster members206 may depend on a transmission power of the cluster head 202. In someembodiments, the transmission power of the cluster head 202 may beadjusted based on a number of terminals within the transmission range204 of the cluster head 202. The transmission power of the cluster head202 may be reduced to reduce the size of the transmission range 204 andpotentially reduce the number of cluster members 206 in the cluster 200.Alternately, the transmission power of the cluster head 202 may beincreased to increase the size of the transmission range 204 andpotentially increase the number of cluster members 206 in the cluster200. In some embodiments, a link budget between each of the clustermembers 206 and the cluster head 202 may be roughly symmetric.

The cluster members 206 may set a default transmission power associatedwith the cluster 200. The default transmission power of each of thecluster members 206 may be based on an estimated path loss between eachof the cluster members 206 and the cluster head 202. The estimated pathloss between each of the cluster members 206 and the cluster head 202may be based on the cluster beacon transmitted by the cluster head 202.Alternately or additionally, the default transmission power of each ofthe cluster members 206 associated with the cluster 200 may be based onpower control commands transmitted by the cluster head 202. The defaulttransmission powers of each of the cluster members 206 in the cluster200 may be different. The cluster members 206 may performcluster-member-to-cluster-member communication 210 directly between twoor more cluster members 206. The cluster-member-to-cluster-membercommunication 210 may generally correspond to the terminal-to-terminalcommunication 112 of FIG. 1.

In some embodiments, the cluster head 202 may manage thecluster-member-to-cluster-member communication 210 within the cluster200. The high received power threshold and/or the low received powerthreshold may be configured by the cluster head 202 through the RRC. Forexample, the cluster head 202 may set a high received power thresholdand/or a low received power threshold for a particularcluster-member-to-cluster-member communication 210. Alternately, thecluster head 202 may set the high received power threshold and/or thelow received power threshold for all or a subset of all thecluster-member-to-cluster-member communication 210 in the cluster 200.

The high received power threshold may be represented by the symbolTh^(H). The high received power threshold may represent a power abovewhich a cluster-member-to-cluster-member communication 210 may besuccessfully received by the cluster members 206 in a bidirectionallink. By way of example, a bidirectional link between the cluster member206 a and the cluster member 206 b may allowcluster-member-to-cluster-member communication 210 between the clustermember 206 a and the cluster member 206 b. Both the cluster member 206 aand the cluster member 206 b may receive thecluster-member-to-cluster-member communication 210 with a power abovethe high received power threshold.

The low received power threshold may be represented by the symbolTh^(L). The low received power threshold may represent a power belowwhich an attempted cluster-member-to-cluster-member communication 210may be unsuccessfully received and/or not received by the clustermembers 206 in an interference link. By way of example, an interferencelink between the cluster member 206 a and the cluster member 206 b maynot allow cluster-member-to-cluster-member communication 210 between thecluster member 206 a and the cluster member 206 b. In some embodiments,an interference link may not be used in cluster-member-to-cluster-membercommunication 210.

A path loss between two of the cluster members 206 may be represented bya symbol PL. A path loss between the cluster member 206 a and thecluster member 206 b may be represented by the symbol PL_(a-b).

A default transmission power associated with the cluster 200 by thecluster member 206 a may be represented by a symbol P^(D) _(a), and adefault transmission power associated with the cluster 200 by thecluster member 206 b may be represented by a symbol P^(D) _(b).

A cluster-member-to-cluster-member communication 210 transmitted by thecluster member 206 b at the cluster member 206 b default transmissionpower may be received at the cluster member 206 a at a received powerrepresented by PL_(a-b)·P^(D) _(b). Conversely, the power of aterminal-to-terminal transmission received at the cluster member 206 bwhen transmitted from the cluster member 206 a at the default power maybe represented by PL_(a-b)·P^(D) _(a).

The cluster member 206 a and the cluster member 206 b may have abidirectional link as a result of the cluster-member-to-cluster-membercommunication 210 being received at both the cluster member 206 a andthe cluster member 206 b with received power equal to or greater thanthe high received power threshold. Put another way, the cluster member206 a and the cluster member 206 b may have a bidirectional link at thedefault transmission powers of the cluster member 206 a and the clustermember 206 b when the following formula 1 and formula 2 are both true.

PL _(a-b) ·P ^(D) _(b) ≧Th ^(H)  Formula 1:

PL _(a-b) ·P ^(D) _(a) ≧Th ^(H)  Formula 2:

In some embodiments, if one or both of formula 1 and formula 2 are nottrue, the transmission power of the cluster terminal 206 a may beincreased and/or the transmission power of the cluster terminal 206 bmay be increased so that the cluster-member-to-cluster-membercommunication 210 is received at the cluster member 206 a and at thecluster member 206 b with a received power equal to or greater than thehigh received power threshold. Put another way, the cluster members 206may change the transmission power of cluster-member-to-cluster-membercommunication 210 to form bidirectional links.

The cluster members 206 may exchange cluster-member-to-cluster-membercommunication 210 over the bidirectional links.

The cluster member 206 a and the cluster member 206 b may have aunidirectional link as a result of the power of thecluster-member-to-cluster-member communication 210 being received atonly one of the cluster member 206 a and the cluster member 206 b with areceived power greater than or equal to the high received powerthreshold. In some embodiments, a unidirectional link may be used forone-way cluster-member-to-cluster-member communication 210. In these andother embodiments, one or more of the cluster members 206 may change thetransmission power of the cluster-member-to-cluster-member communication210 to turn the unidirectional links into bidirectional links.

The cluster member 206 a and the cluster member 206 b may have aninterference link as a result of the power of thecluster-member-to-cluster-member communication 210 being received atboth the cluster member 206 a and the cluster member 206 b with areceived power less than or equal to the low received power threshold.In some embodiments, the interference links may not be used by thecluster members 206 for cluster-member-to-cluster-member communication210. Alternately or additionally, the cluster members 206 may change thetransmission power of the cluster-member-to-cluster-member communication210 to turn the interference links into unidirectional links and/orbidirectional links.

FIG. 6 is a flowchart of an example method 600 of forming a clustergenerally corresponding to the cluster 200 of FIG. 2. In someembodiments, the method 600 may be performed by a terminal generallycorresponding to the terminals 104 of FIG. 1. For example, a terminalwanting to perform terminal-to-terminal communication generallycorresponding to the terminal-to-terminal communication 112 of FIG. 1may perform the method 600.

The method 600 may begin at block 602 by checking for a first clusterbeacon associated with an open cluster. An open cluster may refer to acluster that is not at capacity and may accept one or more additionalcluster members.

The method 600 may continue at block 604 by failing to receive the firstcluster beacon. For example, a terminal performing the method 600 may beoutside of the transmission range of a cluster head associated with anopen cluster. Alternately, one or more cluster beacons associated withclosed clusters may be received. In some instances, the terminalperforming the method 600 may be performed by a terminal that wasformerly a cluster member of a cluster that is no longer in range and/orwas disbanded by the cluster head associated with the cluster.

The method 600 may continue at block 606 by transmitting a secondcluster beacon. A terminal performing the method 600 may thus elect tobecome a cluster head. In these and other embodiments, the secondcluster beacon may include a cluster identifier, a time synchronizationindicator, and/or a cluster status indicator.

In some embodiments, a terminal performing the method 600 may determinewhether the terminal possesses certain qualities before transmitting thesecond cluster beacon and/or electing to become the cluster head. Forexample, the terminal may determine whether the terminal may supportcertain security functions such as authentication, authorization, and/oraccounting (AAA) security functions. Alternately or additionally, theterminal may determine whether the terminal possesses available powerabove a particular threshold, and/or hardware that meets particularperformance thresholds. In some embodiments, terminals may be encouragedto support certain security functions, hardware performance, and/orpower availability before electing to become a cluster head and/ortransmitting the second cluster beacon.

The method 600 may continue at block 608 by associating multipleterminals to the cluster. Once associated with the cluster, the multipleterminals may become cluster members.

In some embodiments, associating the multiple terminals to the clustermay include receiving a request from an individual terminal of themultiple terminals. The request may include the cluster identifierincluded in the second cluster beacon. A response may be transmitted tothe individual terminal. The response may include an identification ofresources allocated for a reply. The reply may be received from theindividual terminal via the resources allocated for the reply. Aconfirmation may be transmitted to the individual terminal. In someembodiments, the confirmation may include a cluster-specific identifierfor the individual terminal.

In some embodiments, associating multiple terminals to the cluster maybe accomplished via a communication process generally corresponding tothe communication process 500 described with reference to FIG. 5.

One skilled in the art will appreciate that, for this and otherprocesses and methods disclosed herein, the functions performed in theprocesses and methods may be implemented in differing order.Furthermore, the outlined steps and operations are only provided asexamples, and some of the steps and operations may be optional, combinedinto fewer steps and operations, or expanded into additional steps andoperations without detracting from the essence of the disclosedembodiments.

For example, in some embodiments, the method 600 may further includereceiving a third cluster beacon. The third cluster beacon may beassociated with a second cluster. The method 600 may include determiningthat the second cluster has a priority relatively higher than a priorityof the cluster and disbanding the cluster. In some embodiments, an RRCsignal may be used to disband the cluster.

In response to disbanding the cluster, the cluster head and the clustermembers may become clusterless and may check for cluster beacons. Insome instances, one or more of the cluster head and/or the clustermembers may receive the third cluster beacon and may join the secondcluster. Alternately or additionally, one or more of the former clustermembers may elect to become cluster heads and may broadcast a newcluster beacon in an attempt to start a new cluster.

The embodiments described herein may include the use of a specialpurpose or general purpose computer including various computer hardwareor software modules, as discussed in greater detail below.

Embodiments described herein may be implemented using computer-readablemedia for carrying or having computer-executable instructions or datastructures stored thereon. Such computer-readable media may be anyavailable media that may be accessed by a general purpose or specialpurpose computer. By way of example, and not limitation, suchcomputer-readable media may include non-transitory computer-readablestorage media including Random Access Memory (RAM), Read-Only Memory(ROM), Electrically Erasable Programmable Read-Only Memory (EEPROM),Compact Disc Read-Only Memory (CD-ROM) or other optical disk storage,magnetic disk storage or other magnetic storage devices, flash memorydevices (e.g., solid state memory devices), or any other storage mediumwhich may be used to carry or store desired program code in the form ofcomputer-executable instructions or data structures and which may beaccessed by a general purpose or special purpose computer. Combinationsof the above may also be included within the scope of computer-readablemedia.

Computer-executable instructions may include, for example, instructionsand data which cause a general purpose computer, special purposecomputer, or special purpose processing device (e.g., one or moreprocessors) to perform a certain function or group of functions.Although the subject matter has been described in language specific tostructural features and/or methodological acts, it is to be understoodthat the subject matter defined in the appended claims is notnecessarily limited to the specific features or acts described above.Rather, the specific features and acts described above are disclosed asexample forms of implementing the claims.

As used herein, the terms “module” or “component” may refer to specifichardware implementations configured to perform the operations of themodule or component and/or software objects or software routines thatmay be stored on and/or executed by general purpose hardware (e.g.,computer-readable media, processing devices, etc.) of the computingsystem. In some embodiments, the different components, modules, engines,and services described herein may be implemented as objects or processesthat execute on the computing system (e.g., as separate threads). Whilesome of the system and methods described herein are generally describedas being implemented in software (stored on and/or executed by generalpurpose hardware), specific hardware implementations or a combination ofsoftware and specific hardware implementations are also possible andcontemplated. In this description, a “computing entity” may be anycomputing system as previously defined herein, or any module orcombination of modulates running on a computing system.

All examples and conditional language recited herein are intended forpedagogical objects to aid the reader in understanding the invention andthe concepts contributed by the inventor to furthering the art, and areto be construed as being without limitation to such specifically recitedexamples and conditions. Although embodiments of the present inventionshave been described in detail, it should be understood that the variouschanges, substitutions, and alterations could be made hereto withoutdeparting from the spirit and scope of the invention.

What is claimed is:
 1. A method comprising: checking for a first clusterbeacon associated with a first cluster, the first cluster being an opencluster; transmitting a second cluster beacon associated with a secondcluster in response to failing to receive the first cluster beacon;receiving a first request in response to transmitting the second clusterbeacon, the first request including a request by a first terminal tojoin the second cluster; and receiving a second request in response totransmitting the second cluster beacon, the second request including arequest by a second terminal to join the second cluster.
 2. The methodof claim 1, further comprising: transmitting a first response to thefirst terminal, the first response including an identification ofresources allocated for a first reply; receiving the first reply fromthe first terminal via the resources allocated for the first reply;transmitting a first confirmation to the first terminal, the firstconfirmation configured to confirm receipt of the first reply;transmitting a second response to the second terminal, the secondresponse including an identification of resources allocated for a secondreply; receiving the second reply from the second terminal via theresources allocated for the second reply; and transmitting a secondconfirmation to the second terminal, the second confirmation configuredto confirm receipt of the second reply.
 3. The method of claim 2,wherein: the first confirmation includes a first cluster-specificidentifier for the first terminal; and the second confirmation includesa second cluster-specific identifier for the second terminal.
 4. Themethod of claim 2, wherein: the second cluster beacon includes: a timesynchronization indicator; and a cluster identifier associated with thesecond cluster; the first request includes the cluster identifier; andthe second request includes the cluster identifier.
 5. The method ofclaim 1, wherein the second cluster beacon further includes a clusterstatus indicator configured to indicate a relative available capacity ofthe second cluster.
 6. The method of claim 1, further comprising:receiving a third cluster beacon; determining that the third clusterbeacon is associated with a third cluster having a priority higher thanthe second cluster; and disbanding the second cluster in response todetermining that the third cluster has a priority higher than the secondcluster.
 7. The method of claim 1, further comprising transmitting ahigh received power threshold to at least one of the first terminal andthe second terminal.
 8. A method of joining a first cluster including afirst cluster head, the method comprising: receiving a first clusterbeacon from the first cluster head, the first cluster beacon associatedwith the first cluster, the first cluster beacon including first clustercontrol information; receiving a second cluster beacon from a secondcluster head, the second cluster beacon associated with a secondcluster, the second cluster beacon including second cluster controlinformation; choosing to join the first cluster based at least in parton the first cluster control information and the second cluster controlinformation; and transmitting a request to join the first cluster to thefirst cluster head.
 9. The method of claim 8, wherein: the first clustercontrol information includes a first cluster identifier; the secondcluster control information includes a second cluster identifier; andthe request to join the first cluster includes the first clusteridentifier.
 10. The method of claim 8, wherein: the first clustercontrol information includes a first time synchronization indicator; thesecond cluster control information includes a second timesynchronization indicator different from the first time synchronizationindicator; and choosing to join the first cluster is further based atleast in part on the first time synchronization indicator and the secondtime synchronization indicator.
 11. The method of claim 8, wherein: thefirst cluster control information includes a first cluster statusindicator configured to indicate a first relative available capacity ofthe first cluster; the second cluster control information includes asecond cluster status indicator configured to indicate a second relativeavailable capacity of the second cluster, the second cluster statusindicator different from the first cluster status indicator; andchoosing to join the first cluster is further based at least in part onthe first cluster status indicator and the second cluster statusindicator.
 12. The method of claim 8, wherein choosing to join the firstcluster is further based at least in part on a first relative mobilityof the first cluster head and a second relative mobility of the secondcluster head, the first relative mobility based at least in part on thefirst cluster beacon, and the second relative mobility based at least inpart on the second cluster beacon.
 13. The method of claim 8, furthercomprising: choosing to join the second cluster; transmitting a requestto join the second cluster; receiving a communication from the firstcluster; and transmitting the communication to the second cluster. 14.The method of claim 8, further comprising: receiving a high receivedpower threshold from the first cluster head; and increasing aterminal-to-terminal transmission power based at least in part on thehigh received power threshold.
 15. A terminal including a non-transitorycomputer-readable medium having encoded therein programming codeexecutable by a processor to perform operations comprising: checking fora first cluster beacon from a first cluster head, the first clusterbeacon associated with a first cluster, the first cluster beaconincluding first cluster control information; checking for a secondcluster beacon from a second cluster head, the second cluster beaconassociated with a second cluster, the second cluster beacon includingsecond cluster control information; in response to receiving the firstcluster beacon and failing to receive the second cluster beacon,transmitting a request to join the first cluster; and in response toreceiving the first cluster beacon and receiving the second clusterbeacon: choosing to join the first cluster based at least in part on thefirst cluster control information and the second cluster controlinformation, and transmitting a request to join the first cluster. 16.The terminal of claim 15, wherein choosing to join the first clusterbased at least in part on the first cluster control information and thesecond cluster control information includes prioritizing the firstcluster relative to the second cluster based at least in part on a firsttime-synchronization indicator of the first cluster control informationand a second time-synchronization indicator of the second clustercontrol information.
 17. The terminal of claim 16, wherein prioritizingthe first cluster relative to the second cluster is further based atleast in part on one or more of: a first cluster status of the firstcluster control information and a second cluster status of the secondcluster control information; a first relative mobility of the firstcluster head and a second relative mobility of the second cluster head;and a first cluster identifier of the first cluster control informationand a second cluster identifier of the second cluster controlinformation.
 18. The terminal of claim 15, wherein in response tofailing to receive the first cluster beacon and failing to receive thesecond cluster beacon, the operations further include: electing tobecome a third cluster head; and transmitting a third cluster beaconassociated with a third cluster.
 19. The terminal of claim 18, theterminal including: an authentication security function; anauthorization security function; and an accounting security function.20. The terminal of claim 18, wherein the operations further include:checking for a fourth cluster beacon from a fourth cluster head, thefourth cluster beacon associated with a fourth cluster, the fourthcluster beacon including fourth cluster control information; determiningvia the fourth cluster control information that the fourth cluster has ahigher priority relative to the third cluster; and disbanding the thirdcluster.